A sandwich component should be generally understood as meaning a component that is made up of layers of the same material or different materials. In the simplest case, sandwich components includes two cover layers: an upper cover layer and a lower cover layer, as well as a core layer, which is arranged between the upper cover layer and the lower cover layer. A connection between the individual layers usually takes place by pressing via a suitable tool, such as, for example, a press.
Such sandwich components are used in many different areas. In recent years, however, their importance particularly as a structural component in the area of lightweight automobile construction has increased enormously. Structural component means in this context that the component has a three-dimensional shape, it is not necessarily a load carrying component. It can be for example a front flap or a trunk lid or a door of a vehicle.
The related art discloses many different approaches to the production of structural components.
For example, a process for the production of a sandwich component for use as a structural component of a vehicle is described in German Patent Publication No. DE 10 2012 222 376 A1. This involves first arranging an inner cover layer in a tool, arranging a core layer that is porous at least in certain portions on the inner cover layer and in turn arranging an outer cover layer on said core layer. After the described arrangement of the individual layers, a process pressure is produced against the two cover layers and a core pressure is produced in the core layer to equalize the pressure with respect to the process pressure. In this way, the core layer is not subjected to excessive process pressure and does not have to be over dimensioned in terms of its stability.
German Patent Publication No. DE 10 2013 013 419 A1 discloses a continuous production process for producing sandwich components that vary on the visible side, an apparatus for producing the sandwich component and a sandwich component that can be produced thereby. Starting with a cover layer/core layer/cover layer stack, wherein the cover layers consist of layers of fibrous thermoplastic material, the process presented in this document for producing the sandwich component comprises a first step of heating the sandwich arrangement, wherein the sandwich arrangement is heated until the thermoplastic material of the layer of fibrous material at least begins to flow. The heating takes place in a heating tool, for example a heating press. When the heating press is used, the pressing pressure produced has the effect that the layers of fibrous thermoplastic material adhere to the honeycomb core (core layer). In the next process step, a decorative layer with a foam layer is arranged on the heated sandwich arrangement in such a way that the foam layer is facing the cover layer. The viscous thermoplastic of the cover layer brings about adhesive bonding of the foam layer to the sandwich arrangement. After that, the surface of the decorative layer is adapted via a form template to the surface structure that the finished sandwich arrangement should have. For this purpose, one or more form template(s) is/are arranged on one or both basic mould surfaces of the compression moulding tool. The final step of the process is represented by the cooled compression moulding via a moulding press.
Similarly, European Patent Publication No. EP 1 897 680 A1 describes a process for producing a fibre-reinforced sandwich component with a honeycomb core, wherein the honeycomb core is only closed on one side via a cover layer, but the honeycombs of the honeycomb layer are closed on both sides. The process in that case comprises the steps of: producing a lay-up comprising the honeycomb core, as well as, at least on one side of the honeycomb core, arranged from the inside to the outside, a curable adhesive layer, a barrier layer and a fibre layer; confining the lay-up in a gas-tight space; producing a vacuum in this gas-tight space; complete or partial curing of the adhesive layer between the honeycomb core and the barrier layer under this vacuum, so that the honeycomb cells are at least partly evacuated before they are closed by the barrier layer; and after complete or partial curing of the adhesive layer, infusing the fibre layer under vacuum with a matrix material, and curing the matrix material under vacuum.